1. Field
Example embodiments provide an organic solar cell.
2. Description of the Related Art
An organic solar cell is a photoelectric conversion device that transforms solar energy into electrical energy, and has attracted attention as an infinite but pollution-free next generation energy source.
An organic solar cell includes a photoactive layer including p-type and n-type organic semiconductors, and produces electrical energy by transferring electrons and holes to the n-type and p-type semiconductors, respectively, and then collecting the electrons and holes in each electrode when an electron-hole pair (EHP) is produced by solar light energy absorbed in a photoactive layer inside the semiconductors.
However, an organic semiconductor absorbs only light of a predetermined or given wavelength region due to inherent characteristics of the material, and therefore light of relatively wide wavelength regions are unfavorably not absorbed.
In order to solve the above limitation, a tandem organic solar cell including a plurality of sub-solar cells (hereinafter referred to as “sub-cells”) absorbing light of different wavelength regions is suggested.
A tandem organic solar cell is capable of absorbing light of relatively wide wavelength regions and thus increases light absorbance.
However, an entire output current of a tandem organic solar cell is determined by a sub-cell having the lowest output current of a plurality of sub-cells, and thus excessive charges of sub-cells having a higher output current do not contribute to output and performance of a tandem organic solar cell may be deteriorated.